1. Field of the Invention
This invention relates to an improved ebullated bed hydrocracking process. In the improved process fluid catalytic cracking catalyst fines are introduced into the reactor and as a result sediment formation in the hydrocracked product oil is reduced.
2. Description of Other Relevant Methods in the Field
The ebullated bed process comprises the passing of concurrently flowing streams of liquids or slurries of liquids and solids and gas through a vertically cylindrical vessel containing catalyst. The catalyst is placed in random motion in the liquid and has a gross volume dispersed through the liquid medium greater than the volume of the catalyst when stationary. The ebullated bed process has found commercial application in the upgrading of heavy liquid hydrocarbons such as vacuum residuum or atmospheric residuum or converting coal to synthetic oils. The ebullated bed process is generally described in U.S. Pat. No. Re. 25,770 issued Apr. 27, 1965 to E. S. Johanson incorporated herein by reference.
U.S. Pat. No. 3,681,231 to S. B. Alpert et al. discloses an ebullated bed process for the production of fuels such as diesel oil. A crude feedstock and an aromatic diluent is passed to an ebullated bed at a temperature of 600.degree. F. to 900.degree. F., pressure of 500 to 5000 psig and a hydrogen partial pressure in the range of 65% to 95% of total pressure. It was found that 20 to 70 vol % of an aromatic diluent having a boiling point in the range of 700.degree. F. to 1000.degree. F. (heavy gas oil) injected in the feed reduced the amount of insoluble material in the product.
U.S. Pat. No. 4,446,002 to C. W. Siegmund teaches a process for suppressing the precipitation of sediment in unconverted residuum obtained from a virgin residuum conversion process. The process comprises blending the unconverted residuum with an effective amount of a virgin residuum.
U.S. Pat. No. 3,725,247 to A. R. Johnson et al. teaches hydrogenation of residuum in an ebullated bed process. In the drawing is shown two methods of catalyst addition. In the first method, catalyst is added to the ebullated bed with the feed and in the second method catalyst is added by means of a discrete catalyst loading system.